Multiple polydispersed fuel emulsion

ABSTRACT

Multi faceted technology for the combustion and transportation of emulsified hydrocarbon fuel. The fuel comprises a composite of a plurality of hydrocarbon in water emulsions. The composite emulsion has a unimodal hydrocarbon particle distribution, with the hydrocarbon being present in an amount of between 64% and 90% by volume.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is the first application filed for the present invention.

TECHNICAL FIELD

The present invention relates to a hydrocarbon emulsion formation wherethe emulsion has a plurality of particle modal distributions and furtherrelates to a method of transporting the emulsion.

BACKGROUND OF THE INVENTION

Emulsified hydrocarbon fuels have become increasingly important as auseful fuel for steam generation in power plant and other steam raisingfacilities to replace coal and petroleum coke, has environmentaldrawbacks, and natural gas which is relatively more expensive. The highcost of natural gas has particular ramifications in the petroleumprocessing art and specifically in the steam assisted gravity drainagetechnique (SAGD) as related to the production of heavy oils and naturalbitumens. As is known, the SAGD and congener techniques require the useof steam turbines for injecting steam into a subterranean formation tomobilize highly viscous hydrocarbon material. Conventionally, naturalgas has been used to fire the steam generators, however, this isunattractive from a financial point of view and has other inherentdrawbacks. With the advent of emulsified hydrocarbons, especially thosemanufactured from hydrocarbons or their products from indigenoushydrocarbon production, it has been found that the heat content isadequate to burn in a steam generation environment.

One of the first pioneering fuels in this field was Orimulsion,manufactured in Venezuela by Bitor, and shipped worldwide to supplypower generation plants. Building on the success of Orimulsion, otheremulsified fuels have been developed such as MSAR™ (Multi-PhaseSuperfine Atomized Residue), by Quadrise Ltd. and now further developedby Quadrise Canada Fuel Systems, Inc. MSAR™ is an oil-in-water emulsionfuel where the oil is a hydrocarbon with an API gravity between 15 and−10. Typical oil-water ratios lie in the range 65% to 74%. Because ofthe presence of oil droplets in water, MSAR™ is essentially apre-atomized fuel. This means that the burner atomizer does not domechanical work to produce oil droplets, as in conventional fuel oilcombustion, but that it is the emulsion manufacturing equipment thatproduces the oil droplets. Pre-atomization literally means ‘before theatomizer’ and so the MSAR™ manufacturing equipment is essentially theatomizer of this process. Typical mean droplet size characteristics ofMSAR™ are around 5 microns, whereas typical mean droplet sizecharacteristics produced during fuel oil atomization in a burneratomizer are between 150 and 200 microns. Therefore, the enormousincrease in surface area brought about by producing much smallerdroplets in the MSAR™ production process, compared with a conventionalburner atomizer, leads to much more rapid and complete combustion,despite the fact that there are significant quantities of water present.In addition, when MSAR™ passes through a conventional atomizer, as itmust do in order to be combusted, 150-200 micron water dropletscontaining the 5 micron oil droplets are formed. Water therefore findsitself located in the interstitial zones between each assembly of oildroplets. This interstitial water, between the oil droplets,spontaneously vaporizes and this leads to further break-up of thealready small (5 micron) droplets. This process is known as secondaryatomization. Because of this secondary atomization and the earlierdescribed pre-atomization, MSAR™ has been found to be a particularlyeffective fuel, with a carbon burnout rate of 99.99%. Carbon burnout isobviously an important aspect of any combustion process and the factthat MSAR™ carbon burnout is so high, substantially reduces the amountof carbon coated ash that collects in the burner and/or furnace. As isknown, if the carbon burnout is low, then carbon will deposit with ashon boiler surfaces and will effectively lead to the production of coke;this leads to inefficiencies and/or inoperability in the overallprocess. By providing a 99.99% carbon burnout rate, these problems areobviated.

Whilst the extremely small droplet size associated with MSAR™ hasdistinct advantages for the combustion process, it has disadvantages forthe handling and pumping processes because the smaller the droplets, themore viscous the MSAR™. Therefore, in order to further advance emulsionfuel technology, present research, conducted by other organizations, hasdeveloped means by which the extremely small droplet size can bemaintained whilst simultaneously reducing viscosity leading toimprovements in storage, handling and transportation generally.Consequently, research has gone in the direction of bimodal emulsions,i.e. emulsions which have two distinct droplet size peaks in theirdroplet size profile.

This is reflected in, for example, U.S. Pat. No. 5,419,852 issued May30, 1995 to Rivas, et al and U.S. Pat. No. 5,503,772, issued Apr. 2,1996 to Rivas et al, inter alia. In these references, specific blends ofindependently produced and discretely different characteristic emulsionsare used to describe the invention. The conclusion is made that thebimodal emulsions can be prepared to reduce viscosity and illustratethat the final emulsion is distinctively bimodal in its physicalcharacteristics.

Although it is desirable to have a bimodal emulsion, this technology isnot without limitation. It is known in the art that the larger theaverage particle size is, the lower the viscosity of the mixture.Unfortunately, the larger the particles in an emulsified fuel, thegreater the length of time it takes for the oil droplet to combust andtravel down the furnace which results in the requirement for a longerfurnace. In the event that the furnace is of an insufficient length forthe selected fuel, then unburnt hydrocarbon material and/or smoke becomeundesirable attributes. In this manner, the existing technology islimited by the equipment used which can add costs, complications andother problems related to pollution in the overall process.

Given the state of the art, it has now been recognized that theviscosity drives the overall system towards bigger oil droplets in thefuel, while the combustion results in the driving of the system towardssmaller oil droplets. Accordingly, it would be desirable to have aformulation that results in the change in the particle size distributionof the fuel emulsion to reduce viscosity, but also to improvecombustion. These latter two properties are most desirable to provide avery efficient high enthalpy emulsified fuel. Having the formation of anemulsion with the above noted properties as a goal, a novel approach wastaken to resolve these properties into an emulsion.

It was found particularly effective to look at the packing of particlesin the prior art and adopt this technology. This approach had notpreviously been applied to the field of emulsions for the purpose ofgenerating a composite emulsion having the most desirable properties,namely a broad particle distribution composed of n-modal distributions,but maintaining, as far as is practically possible, the n-modaldistributions as a single peak or unimodal distribution.

Representative of the particle packing references was gleaned from theJournal of Computational Physics 202 (2005), 737-764, and particularlyan article entitled Neighbor list collision-driven molecular dynamicssimulation for non-spherical hard particles. I. Algorithmic details. Ageneral algorithm for a system of particles having relatively smallaspect ratios with small variations in size. The article was authorizedby Donev et al. A further article by the same author entitled, Neighborlist collision-driven molecular dynamics simulation for non-sphericalhard particles. II. Applications to ellipses and ellipsoids, Journal ofComputational Physics 202 (2005), 765-793, was also reviewed. Othergeneral references in the spherical packing technology include: thearticle Modeling the packing of granular media by dissipative particledynamics on an SGI Origin 2000, using DL _(—) POLY with MPI, Elliott etal; Packing and Viscosity of Concentrated Polydisperse Coal-WaterSlurries, Veytsman et al, Energy and Fuels 1998, 12, 1031-1039; IsRandom Close Packing of Spheres Well Defined? Physical Review Letters, 6Mar. 2000, Torquato et al.; and The random packing of heterogeneouspropellants, KNOTT et al.

In view of the prior art in the emulsion field, there still exists aneed for an emulsion which facilitates changes in particle sizedistribution of the fuel emulsion to reduce viscosity, but also onewhich has improved combustion and does not lead to poor carbon burnout.The technology herein provides for burn optimization of the emulsion.

By applying the packing models from solid fuel to the instanttechnology, it was found that the wider the particle size distribution,the lower the viscosity of the emulsion.

The present invention has now collated the most desirable properties fora fuel emulsion where the final emulsion is effectively a compositeemulsion of at least two precursory emulsions and which compositeemulsion provides for a unimodal distribution, i.e. a single peak,emulsion as opposed to bimodal distribution which is exemplified in theprior art. Unimodal as used herein, refers to a majority peak with thepotential for shoulders, but absent discrete peaks.

The present invention has successfully unified unrelated technologies toresult in a particularly efficient composite fuel emulsion.

SUMMARY OF THE INVENTION

One aspect of the present invention is to provide a substantiallyimproved atomized fuel emulsion, which emulsion is a composite fuelemulsion having very desirable burn properties, calorific value andwhich can be custom designed for burning in any furnace or burningarrangement which is vastly different from the prior art.

According to a further aspect of one embodiment of the presentinvention, there is provided an emulsified hydrocarbon fuel, comprisinga composite of a plurality of hydrocarbon-in-water emulsions, thecomposite emulsion having a unimodal hydrocarbon particle distribution,the hydrocarbon being present in an amount of between 64% and 90% byvolume.

As noted herein previously with respect to the prior art, high oilcontent in the oil-in-water emulsion has been recognized previously,however, the emulsion formed in the prior art is bimodal. By making useof the instant technology, not only is the hydrocarbon contentexceedingly high, but the viscosity is reduced for the overall systemrelative to the independent viscosities of the precursor emulsionsforming the composite and further, the carbon burnout rate isparticularly attractive at greater than four nine effectiveness.

The precursor emulsions may contain the same hydrocarbon material ordifferent hydrocarbon materials depending upon the specific use of theemulsion. In addition, the particle size distributions and droplet sizemay be the same or different. In the instance where the sizedistributions are the same, the hydrocarbon material will be differentin the discrete emulsions. As a further possibility, the compositeemulsion may be a composite emulsion combined with a hydrocarbon inwater emulsion. Similar to that noted above, the composite emulsion andhydrocarbon in water may comprise the same or different hydrocarbonmaterial, same or different droplet size and/or the same or differentparticle size distribution.

According to a further aspect of one embodiment of the present inventionthere is provided a method of formulating a composite emulsion made fromdifferent hydrocarbon materials which possess widely differingviscosities and therefore widely differing emulsion preparationtemperatures. Consequently, the precursor emulsion which is made at thelower temperature can be used as a cooling agent when mixed with theprecursor emulsion which is made at the higher temperature. Thisobviates or reduces the need to use heat exchangers to reduce thetemperature of emulsions which are made above 100 deg C. to below 100deg C. prior to storage.

According to a further aspect of one embodiment of the present inventionthere is provided a method of formulating a composite emulsion havingunimodal particle distribution with reduced viscosity relative toprecursor emulsions used to form said composite emulsion: providing asystem having an n-modal particle distribution; forming a precursoremulsion for each n-modal distribution present in the system, eachprecursor emulsion having a characteristic viscosity; and mixingprecursor emulsions to form the composite emulsion with a unimodal sizedistribution and reduced viscosity relative to each precursor emulsion.

As briefly discussed herein previously, it has been found that by makinguse of the composite emulsion, the same has a viscosity which readilyfacilitates transportation, despite the high content of hydrocarbonmaterial present in the emulsion. It is believed this is due to theunimodal particle size distribution which, inherently provides a broaderspectrum of particle sizes. This, in turn, commensurately providesadvantage in mixture viscosity.

A still further aspect of one embodiment of the present invention is toprovide a method for transporting viscous hydrocarbon materialcomprising: providing a source of hydrocarbon material; generating aplurality of emulsions of the hydrocarbon material, each emulsion havinga characteristic viscosity, each emulsion having a different particlesize distribution; mixing the plurality of emulsions in a predeterminedratio to form a composite emulsion having a lower viscosity relative tothe plurality of emulsions; and mobilizing the composite emulsion.

A still further aspect of one embodiment of the present invention is amethod of maximizing viscous hydrocarbon content in an aqueous systemfor storage or transport, comprising: providing a hydrocarbon emulsionhaving a hydrocarbon internal phase volume sufficiently high such thatthe droplets in the emulsion are aspherical; converting the emulsion atleast to a bimodal emulsion system; forming at least two precursoremulsions from the system; mixing the precursor emulsions in apredetermined ratio to effect reduced viscosity; and synthesizing acomposite emulsion from the precursor emulsions having the reducedviscosity.

A still further aspect of one embodiment of the present invention is amethod of formulating a composite emulsion having unimodal particledistribution with reduced viscosity relative to precursor emulsions:providing a system having an n-modal particle distribution; forming aprecursor emulsion for each modal distribution present in the system;each the precursor emulsion having a characteristic viscosity; forming aplurality of composite emulsions each having a unimodal sizedistribution and reduced viscosity relative to each the precursoremulsions; and mixing the composite emulsions to form an amalgamatedcomposite emulsion having a unimodal particle distribution and reducedviscosity relative to the viscosity of the composite emulsions.

In accordance with another beneficial aspect of one embodiment of thepresent invention, it was found that the HIPR (High Internal PhaseRatio) emulsions, which have extremely high hydrocarbon material contentin the emulsion, could also be transported efficiently. By making use ofthe high internal phase ratio emulsion, it was discovered that theseemulsions can be converted to at least a bimodal or n-modal emulsionsystem depending upon the number of particle size distributions withinthe HIPR emulsion and then these individual bimodal emulsions could beformed into precursor emulsions and mixed to form a composite emulsionin accordance with the methodology previously discussed herein. In thismatter, aspherical or substantially non-spherical oil in water particlescan be reconfigured or converted into discreet modes for individualemulsion synthesis with subsequent mixing for composition of a morefavorably transportable composite emulsion. This has particular utilityin permitting mobilization of high hydrocarbon content material withoutexpensive unit operations conventionally attributed to processes in theprior art such as pre-heating, the addition of diluents or otherviscosity reducing agents. The material can simply be converted, to acomposite emulsion and once so converted, inherently has the sametransportation advantages of the composite emulsions discussed hereinpreviously.

A method of modifying at least one of the combustion, storage andtransportation characteristics of an emulsion during at least one ofpre-formation, at formation and post formation, comprising: providing anemulsion; treating the emulsion to a unit selected from the groupsconsisting of additive addition, mechanical processing, chemicalprocessing, physical processing and combinations thereof; and modifyingat least one characteristic of the characteristics of the emulsion fromtreatment.

BRIEF DESCRIPTION OF THE DRAWINGS

Having thus generally described the invention, reference can now be madeto the accompanying drawings illustrating preferred embodiments and inwhich:

FIG. 1 is a schematic illustration of the overall synthesis mechanism ofthe instant technology;

FIG. 1A is a schematic illustration of a variation in the overallsynthesis mechanism of the instant technology;

FIG. 2 is a graphical illustration of particle size as a function ofshear;

FIGS. 3A and 3B are graphical illustrations of viscosity as a functionof droplet size ratio;

FIG. 4 is graphical illustration of percentage of oil in the emulsion asa function of further length;

FIG. 5 is a graphical illustration of two precursors and a compositeemulsion of a surfactant in 70% NE Alberta bitumen for a median particlesize of 5 μm and 24 μm;

FIG. 6 is a graphical illustration of the composite emulsion viscosityfor varying percentages of the same median particle size;

FIG. 7 is a graphical illustration of a two modal distribution for NorthEastern Alberta bitumen particles with two particle sizes (5 microns and10 microns);

FIG. 8 is a graphical illustration of viscosity as a function of thepercentage of 5 micron MSAR™ used in the precursory emulsion andpercentage of 10 micron MSAR™ used in the second precursory emulsion;

FIGS. 8A through 8C illustrate particle distributions for compositeemulsions formed from the 5 and 10 micron individual emulsions for 5 and10 micron percentages of 20% and 80%, 50% and 50% and 80% and 20%,respectively;

FIG. 9 illustrates the individual distributions for a 6 micron 12 micronmode where both precursory emulsions are formed using a surfactant and a70% content of refinery residue;

FIG. 10 illustrates a viscosity as a function of the MSAR™ mixturecomposed of 5 microns in the first emulsion and 12 microns in the secondemulsion;

FIGS. 10A through 10C illustrate the result of the particle distributionin the composite emulsions for the 6 and 12 micron particles in thefollowing percentages: 20% and 80%, 50% and 50% and 80% and 20%,respectively;

FIG. 11 is a graphical illustration of the precursors where emulsionnumber 1 comprises 6 micron median particle size distribution andemulsion to a 16 micron median particle size distribution;

FIG. 12 is a graphical representation of the viscosities of the MSAR™mixtures composed of 6 micron and 16 micron 80/100 Asphalt MSAR™;

FIGS. 12A through 12C illustrate varying percentages of 6 micron and 16micron particles, namely 20% and 80%, 80% and 20%, and 50% and 50%,respectively;

FIG. 13 is front view of a burner where the illustration is of a NorthEastern Alberta bitumen MSAR™ fuel number 1 being combusted;

FIG. 14 is a side view of the flame illustrated in FIG. 13;

FIG. 15 is an illustration of the coke deposits on the nozzle subsequentto the combustion of the fuel being burned in FIGS. 13 and 14;

FIG. 16 is a view similar to FIG. 15 after a second burning run of MSAR™fuel 1;

FIG. 17 is a view of the combustion from the burner of the North EasternAlberta bitumen MSAR™ fuel 2;

FIG. 18 is a photograph of the nozzle after combustion of the MSAR™ fuel2 illustrating the coke deposit;

FIG. 19 is a figure depicting the flame generated from the burning ofthe North Eastern Alberta bitumen MSAR™ composite fuel between the MSAR™fuel 1 and MSAR™ fuel 2;

FIG. 20 is a side view of the flame of FIG. 19; and

FIG. 21 is an illustration of the burner nozzle illustrating the minimumdeposition of coke on the nozzle.

It will be noted that throughout the appended drawings, like featuresare identified by like reference numerals.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to FIG. 1, shown is the overall synthesis mechanismglobally denoted by numeral 10. The synthesis mechanism includes twobroad steps denoted by numerals 12 and 14. In step 12, a hydrocarbonmaterial 16 is mixed with water 20 containing a surfactant 18 and thematerial, as a mixture, is mixed in a mixing device 22.

The hydrocarbon material may comprise any hydrocarbon material fuel, nonlimiting examples of which include natural gas, bitumen, fuel oil, heavyoil, residuum, emulsified fuel, multiphase superfine atomized residue(MSAR™), asphaltenes, petcoke, coal, and combinations thereof. It isdesirable to employ hydrocarbon material of less than 18 API. The use ofan emulsion stabilizer (a chemical composition which presents prematurephase separation of the emulsion), stabilizes phase separation. Thesurfactants are useful for this as well as a host of other members inthe class of stabilizers.

In terms of the surfactants, it is well known in this art that thesurfactants may be non-ionic, zwitterionic, cationic or anionic ormixtures thereof. Further, they may be in a liquid, solid or gaseousstate. It is well within the purview of the scope of this invention touse combinations of materials to achieve a properly dispersed systemnormally attributable to emulsions.

The mixer may comprise any suitable mixer known to those skilled in theart. Suitable amounts for the emulsion stabilizer or surfactant comprisebetween 0.01% by weight to 5.0% by weight of the emulsion with thehydrocarbon comprising any amount up to 90% by weight. In the example, amixer such as a colloidal mill, is used. Once the materials aresubjected to the colloidal mill a first precursor emulsion 24 isgenerated. Similar steps are effected to result in the second precursoryemulsion 24′, with common steps from the preparation of emulsion onebeing denoted by similar numerals with prime designations.

Once precursor emulsion 24 and the second precursor emulsion 24′ areformed, the two are introduced into a mixing device 26 which maycomprise a similar shear apparatus as the colloidal mill or more likelya further selected device such as an in-line static mixer.

In the individual emulsions 24 and 24′, one of the emulsions will have asmaller average particle diameter relative to the second emulsion. Theseare then mixed together in a predetermined ratio to form the compositeemulsion 28 which is a multiple polydispersed fuel emulsion. The presetratio can be determined by making use of a particle packing algorithmsuch as that which has been set forth in the discussion of the priorart. The use of this algorithm was previously applied to solid basedrocket fuels and by making use of the algorithm in the synthesis of acomposite emulsion, a very successful result has been encountered. Oneof the particularly attractive results is that the composite emulsionhas a viscosity that is less than the viscosity of the precursoremulsions by a factor of between 3 and 5 times the viscosity of theprecursor emulsion containing the small droplets. A further advantagethat flows from this unification of unrelated technologies is therequirement for lower preheat temperatures in the composite emulsion asopposed to those preheat temperatures required for the previous orprecursor emulsions.

Conveniently, the composite emulsion also has been found to have muchimproved dynamic and static stability and handling (anything in-betweenmanufacture and burner tip, e.g. storage, valves, pipes, tanks, etc)characteristics and therefore easier storage and transportationpossibilities. In burn testing, the composite emulsions provided greaterthan 99.99% carbon burnout, despite the fact that the emulsion containeda high percentage of the hydrocarbon material in water.

Referring now to FIG. 1A, shown is a variation of the overallarrangement shown in FIG. 1. In this embodiment, the process may bemodified at various stages to effect the transportation storage and/orcombustion of the individual components within the emulsions or thecomposite emulsion itself. In this manner, FIG. 1A provides formodification of at least one of the above noted aspects by modificationat the pre-synthesis mixing point prior to the surfactant and waterentering the mill 22 as denoted by numeral 30 or as a further option bymodifying the hydrocarbon prior to introduction to the mill, this stepbeing indicated by numeral 32. As a further possibility, the emulsionmay be modified at the point of fabrication, denoted by numeral 34 orsubsequent to formation at 36. In respect of similar numerals with primedesignations, these steps apply to emulsion number 2 designated bynumeral 24′. As a further possibility, once the first emulsion 24 andsecond emulsion 24′ are introduced, they may modified at mixer 26denoted by numeral 38 or subsequently modified once the compositeemulsion 28 has been formed. This step is denoted by numeral 40.

By the variation in this process as depicted by FIG. 1A, the emulsionmay be modified in terms of combustion, storage and/or transportationcharacteristics during at least one of pre-formation, at formation andpost formation where the modification involves a unit operation selectedfrom at least additive addition, mechanical processing, chemicalprocessing and physical processing, as well as combinations thereof. Theadditive addition will be discussed herein after.

Referring now to FIG. 2, shown is a schematic graphical illustration ofparticle size as a function of the amount of shear. This permits theselection of different particle size distributions for the emulsions bychanging the amount of shear used to make particles for the emulsion. Itis known that the amount of shear is related to the average particlesize and width of distribution as shown in FIG. 2. The lowest dropletsize is related to the parameters used to formulate the emulsion. Theshear amount is increased by increasing the residence time in the mixingdevice, or increasing the speed at which the rotatable mixing devicerotates.

It has been found that it is convenient to maintain the surfactantconcentration relative to the oil content as substantively the same forprecursor emulsions for purposes of stability. This is exemplary only,variations in the concentration of the surfactant can occur dependingupon the final desired characteristics for the composite emulsion. Insituations when different surfactants are used for different compositeemulsions, the surfactants will, for course, be compatible. The exampleshave been discussed previously and other examples will be apparent tothose skilled.

Referring now to FIGS. 3A and 3B, shown are schematic graphicalillustrations of viscosity as a function of a ratio of small dropletsversus big droplets with the larger droplets being represented on theleft hand side of the graphs.

Referring now to FIG. 4, shown is a schematic illustration of thepercent of the oil content in the emulsion as a function of the lengthof furnace required to completely burn the fuel.

Referring now to FIG. 5, shown is pre-mix particle distributions for abimodal system where numeral 1 represents an emulsion containingsurfactant with 70% North Eastern Alberta bitumen with the balancecomprising water. The first distribution was formulated using a highshear mixer at a high revolution. The median particle size in thisdistribution was 5 microns whereas in distribution number 2, the medianparticle size was 24 microns. In the premix it is evident that eachemulsion possesses a distinctly different mean and median droplet size.

FIG. 6 is a graphical representation of viscosity as a function ofpercentage of 5 micron MSAR™ emulsion and 24 micron MSAR™ used in themixture. Inset FIG. 6A is a distribution representation for a 20% 5micron and 80% 24 micron mixture having a characteristic viscosityindicated by the arrow in the graph of FIG. 6, whereas FIG. 6B is aninset where the mixture or composite emulsion contained 80% 5 micronparticle size and 20% 24 micron particle size with the arrow pointing inFIG. 6 to the characteristic viscosity. Finally, inset FIG. 6C depicts a50/50 blend of 24 micron and 5 micron particles with the characteristicof viscosity being indicated by the arrow. From a review of FIGS. 6Athrough 6C, it is evident that the particle distribution representationsare effectively unimodal despite containing two individual emulsionswhich independently possess distinctly different mean and median dropletsizes.

As a further representation, FIG. 7 provides a North Eastern Albertabitumen particle distribution where there is a greater degree of overlapbetween the two modal distributions in view of the median particle size.In this representation, similar materials were used with respect to theprevious discussion with the 5 micron median particle distribution beingrepresented by numeral 1 which occurred at a relatively high speed,whereas peak 2 comprises medial particle distribution of 10 micronswhich was created at a lower speed. This is an example; mixing can occurin a low and high intensity mixer with the rpm selected based on finalrequirements.

FIG. 8 illustrates a viscosity as a function of the percentage of 5micron MSAR™ used in the precursory emulsion and percentage of 10 micronMSAR™ used in the second precursory emulsion. Insets 8A, 8B, and 8Cillustrate particle distributions for composite emulsion formed from the5 and 10 micron individual emulsions for 5 and 10 micron percentages of20% and 80%, 50% and 50%, and 80% and 20%, respectively. Individualarrows from each of insets 8A through 8C are representative of theviscosity of the individual final composite mixtures of insets 8A, 8Band 8C.

In FIG. 9, a further hydrocarbon material was employed for synthesizingthe composite emulsion. FIG. 9 illustrates the individual distributionsfor a 6 micron and 12 micron mode where both precursor emulsions wereformed using a suitable surfactant and a 70% content of refinery tank 9with a balance of water. The contents of the refinery residue areapproximately 10% gas oil and 90% viscous hydrocarbon material. The 6micron distribution was generated at a relatively high speed, whereasthe 12 micron was generated at a lower speed.

FIG. 10 illustrates the viscosity as a function of the MSAR™ mixturecomposed of 5 microns in the first emulsion and 12 microns in the secondemulsion. FIGS. 10A through 10C illustrate the results of the particledistribution in the composite emulsion for the 6 and 12 micron particlesin the following percentages: 20% and 80%, 50% and 50% and 80% and 20%,respectively.

As is evident from the inset illustrations, each has a characteristicviscosity indicated on the graphical representation of FIG. 10. Further,similar to the previous examples noted, the composite emulsion in allcases is effectively unimodal and accordingly provides a broad particlesize distribution.

FIG. 11 tabulates the characteristics of pre-cursor emulsion whereemulsion number 1 comprises 6 micron median particle size distributionand emulsion 2 a 16 micron median particle size distribution. In thisexample, the surfactant was employed as the surfactant with thehydrocarbon material comprising 70% 80/100 Asphalt with the balancebeing water. The 6 micron distribution was formulated using the mill ata relatively high speed where the 16 micron was synthesized at a lowerspeed.

Similar data to the examples presented previously are presented in FIG.12 where the viscosity is represented. Inset FIGS. 12A through 12Crepresent specific composite emulsion formulations of 6 and 16 microndistributions in the following amounts: 20% and 80%, 80% and 20%, and50% and 50%, respectively.

Once again, the composite emulsion demonstrates a unimodal particledistribution with characteristic viscosities for each of the insets 12Athrough 12C.

From the results, it is evident that the instant methodology results inthe desirable formulation of unimodal composite fuel emulsion fromdiscrete precursory emulsions. It is known that the oil content orhydrocarbon material content of oil in water emulsions of the prior artis generally limited to approximately 70% since greater content beyondthis point increases the viscosity of the emulsion exponentially. Thisis clearly contrary to the desired properties that have been achievedwith the instant methodology. By making use of the protocol as set forthherein, the oil content can be increased to up to 90% whilst stillmaintaining relatively low viscosities compared with conventional orHIPR emulsification. It is believed that the packing of the droplets inthe multiple polydispersed fuel emulsions set forth herein issignificantly better in normal emulsions not presenting unimodaldistributions.

A host of very useful features flow from the use of this methodology notonly to make an improved emulsified fuel with higher carbon burnout thanthe individual emulsions in the composite, but also the lower waterrequirement for transportation.

As discussed briefly, one of the major advantages of the instanttechnology is that HIPR emulsions which are characteristically composedof aspherical particles which are generally polyhedral which can beconverted into individual emulsions and then subsequently combined toform a composite mixture having the advantages that flow from theinstant technology. In this manner, the HIPR emulsions can be convertedto provide the desirable properties of a composite emulsion in terms ofhaving a wider particle distribution with reduced viscosity and improvedcombustion. It is a well known fact that HIPR emulsions haveexceptionally high viscosities, and are very shear thinning. It has notbeen previously proposed to convert HIPR emulsions into discreteemulsions for a combination such as that which is disclosed herein toprovide for reduced viscosity with enhanced combustion. It has not beenpreviously recognized to employ HIPR emulsions which are capable ofhaving a 99.99% carbon burnout rate.

With respect to convenience of use, the emulsion technology set forthherein allows the emulsion to be designed for the furnace or burningarrangement individually as opposed to having to design a furnace tospecifically burn the emulsion. The cost savings on this point areextremely substantial; the modification of the emulsion is obviously amuch less involved exercise than having to design and fabricate a newpiece of expensive equipment.

Further, depending upon economics and the requirements for the compositeemulsion the precursor emulsions are not limited in number and are wellwithin the scope of the instant technology to provide an n-modal system.The individual emulsions would have to be formulated and thensubsequently mixed together to form the composite emulsion as anattendant feature to this aspect of the invention, individual groups ofemulsions may be mixed to form composite emulsions and the so formedcomposite emulsions then further mixed to form an amalgamated emulsionof individual composite emulsions. In terms of bi or multi-modaldistributions used to form a composite emulsion, the composite may bereintroduced into a shear or mixing device to form a processed compositeemulsion.

Having now delineated the details of the invention, reference will nowbe made to the following example:

EXAMPLE

Three fuel types were examined:

-   -   1) North Eastern Alberta bitumen MSAR™ fuel 2 with particle size        5.5 μm;    -   2) North Eastern Alberta bitumen MSAR™ fuel 1 with particle size        22 μm; and    -   3) 50/50 mixture of North Eastern Alberta bitumen MSAR™ fuel 1        and MSAR™ fuel 2 with particle size 5-22 μm.

Experiments began with the fuel having the larger droplet (MSAR™ fuel2).

A fuel firing rate of 30 kg/h, lower than the normal 36 kg/h, was usedto avoid possible fuel plugging since the fuel contained larger sizeddroplets. The same fuel firing rate was used for the other fuel types tomaintain consistency among the conditions.

The initial temperature for the MSAR™ fuel 1 was a fuel temperature of85° C. and was slowly increased to 100° C., based on the flamecharacteristics observed.

Other parameters followed for the protocol were:

Atomizing air temperature of 108° C.;

78-79° C. at burner;

Combustion air temperature of 108° C.

O₂ 6.7, 6.2

Parameters observed for the MSAR™ fuel 2 fuel type were:

An atomizing air temperature of 84° C.;

Combustion air temperature of 84° C.;

A fuel temperature of 65° C.; and

O₂ 5.2, 5.3

TABLE 1 Properties of MSAR Fuels (wet basis) 22 μm 50:50 Mixture MSAR 5μm MSAR (22 and 5 μm) Density by Helium Pyrometer 1005 1004 1006 at 15°C., kg/m³ Calorific Value, cal/g 6745 7003 6860 MJ/kg 28.24 29.32 28.72BTU/lb 12141 12605 12348 Water by distillation, wt % 30 30 30 Carbon, wt% 55.4 59.2 58.5 Hydrogen, wt % 11.5 11.0 10.5 Sulphur, wt % 3.29 3.413.45 Nitrogen, wt % <0.50 <0.50 <0.50 Ash, wt % 0.051 0.034 0.049

TABLE 2 Furnace Operating Conditions and Emission Results 50:50 MixtureNatural Gas 22 μm MSAR 5 μm MSAR (22 and 5 μm) Fuel Flow rate, kg/h 2029.69 29.80 29.83 Thermal input GJ/h 1.063 0.839 0.874 0.857 MMBTU/h1.007 0.795 0.828 0.812 KW 295 233 243 239 Temperature, ° C. At tankoutlet — 52.8 53.0 52.8 At burner 29.5 78.4 75.3 76.5 Pressure atburner, kPa — 96 103 96 Mean particle size μm — 22 5 22 &5 Atomizing airFlow rate, kg/h at NTP 39 29 29 25 Temperature at burner, ° C. 23 97 8480 Pressure at burner, kPa 69 21 28 14 Combustion air Flow rate, kg/h atNTP 382 424 433 468 Temperature at burner, ° C. 33 107 83 88 Flue gasFurnace exit temperature, ° C. 406 393 404 431 Flow rate, Nm³/MJ offuel* 0.256 0.364 0.332 0.321 Particulate loading, g/Nm³ — 0.189 0.1240.146 Flue gas analyses, volume basis O₂, % 3.5 3.5 5.79 3.5 5.2 3.5 4.4CO₂, % 9.1 12.9 11.20 13.0 11.7 12.9 12.2 CO, ppm 13 90 78 71 60 46 44NO, ppm 64 231 201 344 290 300 284 SO₂, ppm — 2794 2426 2853 2581 27522603 Flue gas emission, g/MJ of fuel NO_(x) 0.022 0.098 0.129 0.122 SO₂— 2.526 2.452 2.392 Particulate — 0.069 0.042 0.047 Carbon onparticulate, wt %** — 39.2/38.5 33.0/3.4 6.1/2.3 Particulateconcentration, g/g of — 0.0028 0.0018 0.0019 fuel *Calculations based onstoichiometric combustion and oxygen content of flue gas **The carbonresult is an estimate only as filter paper was analyzed along with thepowder sample

TABLE 3 Comparison of Thermal Heat Transfer for Natural Gas and MSARNatural 22 μm 5 μm 50:50 Mixture Gas MSAR MSAR (22 and 5 μm) FuelThermal input, GJ/h 1.063 0.839 0.874 0.857 MMBTU/h 1.007 0.795 0.8280.812 KW 295 233 243 239 Thermal heat transfer, kW Circuit 1–10 123.95116.21 117.38 117.13 Circuit 11–20 23.11 32.45 27.84 33.05 Circuit 21–281.85 1.62 0.97 1.16 Total (1–28) 157.91 150.28 146.19 151.94 Total W/cm²of thermal 1.21 1.16 1.12 1.17 surface Heat transfer rate, kW/MJ 0.1490.208 0.175 0.171 of fuel input Percent of thermal fuel 53.5 64.4 60.163.6 input extracted in thermal plate

From a review of the data presented in the tables and, with specificreference to Table 3 it is evident that the MSAR™ blend or the compositeemulsion provides a high thermal efficiency which exceeds the value forthe 5 μm MSAR™ and approximates the 22 μm MSAR™.

In furtherance of the significant benefits that have been realized inthe composite emulsion, Table 2 provides flue gas emission data whichagain provides evidence that the NO_(x) and SO₂ emissions are veryappealing from an environmental point of view in the blend. It isparticularly note worthy that the MSAR™ blend composite has a lowercarbon content in the particulates and a lower CO concentration in theflue gas than the precursor emulsions, indicating a much better carbonburnout for the composite emulsion.

Perhaps the most appealing group of data is provided for in Table 3where the thermal heat transfer data is indicated. Reference to thepercent of thermal fuel input extracted in the examples clearly providesfor very favourable energy for the composite relative to that fornatural gas.

The data presented herein is further corroborated by FIGS. 13 through21.

Referring to FIG. 13, shown is a photograph of a burner where the NorthEastern Alberta bitumen MSAR™ fuel 1 is being combusted. The flame shapeis illustrated in the Figure.

FIG. 14 illustrates a side view of the flame from the burner of the fuelbeing burned in FIG. 13.

FIGS. 15 and 16 illustrate the coke deposit on the nozzle of the burnerafter the first run of burn, while FIG. 16 illustrates the coke depositon the nozzle of the burner after a second run; the difference beingfairly significant.

FIG. 17 provides a view of the burner during the burn of the NorthEastern Alberta bitumen MSAR™ fuel 2.

FIG. 18 illustrates the coke deposit on the nozzle of the burnersubsequent to the combustion of the MSAR™ fuel 2.

In FIG. 19, the burning of the composite emulsion is indicated in thephotograph. It is interesting to note that the flame shape is much moreconsolidated than the flame shape of the individual precursor emulsionswhen burned. This is further corroborated by FIG. 20, which shows afairly significant flame length and intensity when taken from a sideview of the burner. As discussed herein previously with respect to theburn characteristics and other features of the composite emulsion, FIG.21 illustrates the cleanliness of the flame; the coke deposit on thenozzle subsequent to burning is virtually non-existent when one comparesthis illustration with the coke deposits from FIG. 16 relating to thecombustion of MSAR™ fuel 1.

CONCLUSIONS

Having regard to the photographic data and physical data presentedduring the testing of the composite emulsion, it is evident that thecomposite emulsion has many significant benefits over the burning of theprecursor emulsions and in many cases approximates the beneficialfeatures of burning natural gas. Obviously, the combustion of thecomposite emulsion provides a more desirable energy output from a lowermonoxide emission, lower coke deposits at the burner nozzle, lowersulfur dioxide emissions among other very desirable properties. Asevinced form the Figures, the composite emulsion flame characteristicsprovide for a much brighter and more stable flame with less brownishdiscolouration, lower carbon monoxide emission among other features.

The embodiments of the invention described above are intended to beexemplary only. The scope of the invention is therefore intended to belimited solely by the scope of the appended claims.

1. An emulsified hydrocarbon fuel, comprising a composite of a pluralityof hydrocarbon in water emulsions and emulsion stabilizer, saidcomposite emulsion having a unimodal hydrocarbon particle distribution,said hydrocarbon being present in an amount of between 64% and 90% byvolume.
 2. The emulsified hydrocarbon fuel as set forth in claim 1,wherein said fuel comprises at least two different precursor emulsions.3. The emulsified hydrocarbon fuel as set forth in claim 2, wherein saidprecursor emulsions each contain a different hydrocarbon particle size.4. The emulsified hydrocarbon fuel as set forth in claim 3, wherein saidprecursor emulsions contain the same hydrocarbon material.
 5. Theemulsified hydrocarbon fuel as set forth in claim 3, wherein saidprecursor emulsions contain different hydrocarbon material.
 6. Theemulsified hydrocarbon fuel as set forth in claim 5, wherein eachprecursor emulsion has a different rate of combustion.
 7. The emulsifiedhydrocarbon fuel as set forth in claim 2, wherein said emulsifiedhydrocarbon fuel is a composite emulsion fuel containing at least twodifferent emulsions in a predetermined ratio.
 8. The emulsifiedhydrocarbon fuel as set forth in claim 3, wherein said particle size ofone emulsion is large relative to said particle size of the secondemulsion.
 9. The emulsified hydrocarbon fuel as set forth in claim 7,wherein each precursor emulsion has a characteristic viscosity, saidcomposite emulsion fuel having a viscosity which is less than eachcharacteristic viscosity of each precursor emulsion.
 10. The emulsifiedhydrocarbon fuel as set forth in claim 9, wherein said compositeemulsion has a viscosity between 300% and 500% less than the viscosityof the emulsion containing smaller particles.
 11. The emulsifiedhydrocarbon fuel as set forth in claim 1, wherein said compositeemulsion has a carbon burnout rate of at least 99.99%.
 12. Theemulsified hydrocarbon fuel as set forth in claim 1, wherein saidcomposite has a unimodal particle size distribution formed from mixing abimodal distribution of said at least two precursor emulsions.
 13. Theemulsified hydrocarbon fuel as set forth in claim 1, wherein saidcomposite is a multiple polydispersed fuel emulsion.
 14. The emulsifiedhydrocarbon fuel as set forth in claim 1, wherein said fuel is a liquidfuel emulsified in an aqueous matrix hydrocarbon.
 15. The emulsifiedhydrocarbon fuel as set forth in claim 1, wherein said hydrocarbonmaterial, comprises less than 18 API.
 16. The emulsified hydrocarbonfuel as set forth in claim 1, wherein said emulsion stabilizer ispresent in an amount between 0.01% and 5.0% by weight of said emulsion.17. The emulsified hydrocarbon fuel as set forth in claim 16, whereinsaid emulsion stabilizer is a surfactant. 18-61. (canceled)